This invention is an improvement of the excavator assembly which is the subject matter of co-pending application Ser. No. 013,523 filed Feb. 21, 1979, now U.S. Pat. No. 4,203,626 and over other prior art excavator assemblies mounted on the front of a mounting ring which constitutes the forward portion of the central rotably mounting means. Such assemblies may include a large bearing, pinion gears affixed to the outer race of the bearing, driven by motors affixed to a bulkhead in the center of the shield, a generally conical housing extending rearwardly from the bulkhead and which has manifold means at the rear end for rotationally connecting the hydraulic lines from the power source with the hydraulic lines which operate the excavator through the mounting means.